1. Field of the Invention
The present invention relates to a magnetic rotating apparatus for directly rotating a fan etc. and, more particularly, to a direct-driven magnetic rotating apparatus using the repulsive force between a permanent magnet and an electromagnet or a permanent magnet.
2. Description of the Related Art
It is known in the art to provide various rotating apparatuses using magnetic force and, particularly, permanent magnet motors are typical applications. Magnetic force has attractive force and repulsive force. Most of the application apparatuses use attractive force. However, it is more preferable to use repulsive force in force in view of efficiency and high-speed rotation. The inventor has therefore disclosed an application apparatus using repulsive force in Japanese Patent No. 2,968,918 (Patent Document 1) and JP-A-7-87725 (Patent Document 2).
The invention disclosed in Patent Document 1 will now be described with reference to FIG. 1 and FIG. 2. FIG. 1 is a general view of a magnetic rotating apparatus. FIG. 2 is a diagram illustrating the relationship between the repulsive force and rotation of magnets which are essential parts of the magnetic rotating apparatus. Referring to FIG. 1, a plurality of permanent magnet plates 103a to 103h is mounted to a rotational body 102 fixed to a rotational shaft 101. Electromagnets 104 are provided in the vicinity of the rotational body having the permanent magnet plates. The part of the rotational body having no permanent magnet plate is provided with balancers 105 (105a to 105h) for balancing the rotation.
Referring to FIG. 2, the principle that the rotational body 102 of the magnetic rotating apparatus having such a structure rotates using magnetically repulsive force will be described. The permanent magnet plates 103a to 103h are disposed diagonally relative to the electromagnets 104, or at an angle D relative to the straight line connecting the electromagnet 104 and the rotational shaft 101 so that permanent magnet plates mounted to the rotational body 102 generate repulsive force to the electromagnets 104 disposed in the vicinity thereof and the repulsive force causes torque.
In the magnetic rotating apparatus with such a structure, energization of the electromagnets 104 to rotate the rotational body 102 is controlled as follows: A pulsed current is applied to the electromagnets 104 to generate magnetic force, thereby generating repulsive force between them and the permanent magnet plates 103a to 103h to generate torque due to a vector component of a rotating direction which is part of the repulsive force, thus rotating the rotational body 102. The application of the pulsed current is started when the first permanent magnet plate 103h comes close to the electromagnet 104 and stopped when the last permanent magnet plate 103a separates from the electromagnet 104. During the period the permanent magnet plates 103a to 103h are not present in the vicinity of the electromagnet 104, the electromagnet 104 is not energized but the rotational body 102 rotates by inertia.
An application apparatus incorporating the magnetic rotating apparatus is disclosed in Patent Document 2. The document refers to a motor and a generator constructed of the magnetic rotating apparatus as application apparatus. When the magnetic rotating apparatus is used as motor, other objects, e.g. bus tires are rotated using the shaft of the motor.
The application apparatus using the magnetic rotating apparatus transmits torque using a shaft etc. in the process of transmitting the torque of the magnetic rotating apparatus to a target. This produces the problem of decreasing the transmission efficiency of the torque because of the shaft and the problem of increasing the cost of components including the shaft and upsizing the entire apparatus.
Furthermore, in order to obtain larger torque or higher rotation speed, power consumption of the electromagnet will be increased or the number or size of permanent magnet plates must be increased to have stronger electromagnetic force, posing the problem of increasing cost and size of the apparatus.